geopandas.GeoSeries.build_area#

GeoSeries.build_area(node=True)[source]#

Creates an areal geometry formed by the constituent linework.

Builds areas from the GeoSeries that contain linework which represents the edges of a planar graph. Any geometry type may be provided as input; only the constituent lines and rings will be used to create the output polygons. All geometries within the GeoSeries are considered together and the resulting polygons therefore do not map 1:1 to input geometries.

This function converts inner rings into holes. To turn inner rings into polygons as well, use polygonize.

Unless you know that the input GeoSeries represents a planar graph with a clean topology (e.g. there is a node on both lines where they intersect), it is recommended to use node=True which performs noding prior to building areal geometry. Using node=False will provide performance benefits but may result in incorrect polygons if the input is not of the proper topology.

If the input linework crosses, this function may produce invalid polygons. Use GeoSeries.make_valid() to ensure valid geometries.

Parameters:

nodebool, default True: Perform noding prior to building the areas, by default True.

Returns:

GeoSeries: GeoSeries with polygons

Examples

>>> from shapely.geometry import LineString, Polygon
>>> s = geopandas.GeoSeries([
...     LineString([(18, 4), (4, 2), (2, 9)]),
...     LineString([(18, 4), (16, 16)]),
...     LineString([(16, 16), (8, 19), (8, 12), (2, 9)]),
...     LineString([(8, 6), (12, 13), (15, 8)]),
...     LineString([(8, 6), (15, 8)]),
...     LineString([(0, 0), (0, 3), (3, 3), (3, 0), (0, 0)]),
...     Polygon([(1, 1), (2, 2), (1, 2), (1, 1)]),
... ])
>>> s.build_area()
0    POLYGON ((0 3, 3 3, 3 0, 0 0, 0 3), (1 1, 2 2,...
1    POLYGON ((4 2, 2 9, 8 12, 8 19, 16 16, 18 4, 4...
Name: polygons, dtype: geometry